Car and truck navigation systems based on global positioning system (GPS) receivers have become indispensable aids for both business and pleasure driving. Such systems do not work well, however, when signals from GPS satellites are obscured or unavailable as may happen when driving in a tunnel or urban canyon environment. To combat problems from GPS signal loss, inertial measurement units (IMU) are combined with GPS receivers to provide dead reckoning as a supplement to satellite navigation.
Many of the hardware components necessary to implement a GPS+IMU system are present in so-called “smart” cell phones, personal digital assistants or tablet computers. We use “smart-phone” as short hand to refer to any of these kinds of devices. What is needed are systems and methods to implement a GPS+IMU system for car or truck navigation taking advantage of the display, processor and sensors found in typical smart-phone.